Recent advances in functional brain imaging have identified brain activation profiles that help outline the neural circuitry necessary for many cognitive functions. Using Magnetic Source Imaging (MSI), we have identified aberrant activation profiles that are characteristic of children with dyslexia and shown that successful educational intervention not only results in improved reading performance, but also in normalization of the aberrant brain activation patterns. In the present project we will use MSI in an attempt to identify aberrant activation patterns underlying different types of math disabilities (Aim 1), and to determine whether successful intervention that results in improved performance in arithmetic tasks, results changes in the corresponding brain activity patterns (Aim 2). For Aim 1, 80 third graders (20 per group) with only math disabilities (MD), MD and reading disabilities (RD), only RD, and controls studied in Project 1 (Cognition) will complete MSI studies based on single digit addition and subtraction tasks, and tasks involving number comparison and number concepts. These tasks are expected to differentially activate anterior and posterior components of the complex neural network that mediates number processing. We expect to find differences in the activation patterns associated with MD (mostly biparietal) and MD-RD (mostly left fronto- temporal). In Years 2-3, third graders (20 per group per year) with MD and MD-RD will be randomly assigned to interventions involving a word identification control condition and math instruction conditions involving fact retrieval, procedural knowledge, and both fact retrieval and procedural knowledge. These children will receive MSI scans before and after intervention using addition, number comparison, and number concept tasks. These studies will be repeated with new cohorts of similarly defined third graders in Years 4 and 5, with an arithmetic word problem intervention added to fact retrieval. In both studies, we expect to see significant changes in the brain activation patterns associated with different types of math disabilities in response to successful intervention. This study is conducted in parallel to the MRI studies in Project 3 (MRI) and both should contribute significantly to an understanding of brain function in children with math disabilities.